/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2002,2003-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xerces.internal.impl.xs.util;

import java.lang.reflect.Array;
import java.util.AbstractList;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.NoSuchElementException;

import com.sun.org.apache.xerces.internal.xs.XSObject;
import com.sun.org.apache.xerces.internal.xs.XSObjectList;

/**
 * Containts a list of XSObject's.
 *
 * @author Sandy Gao, IBM
 * @version $Id: XSObjectListImpl.java,v 1.7 2010-11-01 04:40:06 joehw Exp $
 * @xerces.internal
 */
public class XSObjectListImpl extends AbstractList implements XSObjectList {

  /**
   * An immutable empty list.
   */
  public static final XSObjectListImpl EMPTY_LIST = new XSObjectListImpl(new XSObject[0], 0);
  private static final ListIterator EMPTY_ITERATOR = new ListIterator() {
    public boolean hasNext() {
      return false;
    }

    public Object next() {
      throw new NoSuchElementException();
    }

    public boolean hasPrevious() {
      return false;
    }

    public Object previous() {
      throw new NoSuchElementException();
    }

    public int nextIndex() {
      return 0;
    }

    public int previousIndex() {
      return -1;
    }

    public void remove() {
      throw new UnsupportedOperationException();
    }

    public void set(Object object) {
      throw new UnsupportedOperationException();
    }

    public void add(Object object) {
      throw new UnsupportedOperationException();
    }
  };

  private static final int DEFAULT_SIZE = 4;

  // The array to hold all data
  private XSObject[] fArray = null;
  // Number of elements in this list
  private int fLength = 0;

  public XSObjectListImpl() {
    fArray = new XSObject[DEFAULT_SIZE];
    fLength = 0;
  }

  /**
   * Construct an XSObjectList implementation
   *
   * @param array the data array
   * @param length the number of elements
   */
  public XSObjectListImpl(XSObject[] array, int length) {
    fArray = array;
    fLength = length;
  }

  /**
   * The number of <code>XSObjects</code> in the list. The range of valid
   * child node indices is 0 to <code>length-1</code> inclusive.
   */
  public int getLength() {
    return fLength;
  }

  /**
   * Returns the <code>index</code>th item in the collection. The index
   * starts at 0. If <code>index</code> is greater than or equal to the
   * number of nodes in the list, this returns <code>null</code>.
   *
   * @param index index into the collection.
   * @return The XSObject at the <code>index</code>th position in the <code>XSObjectList</code>, or
   * <code>null</code> if that is not a valid index.
   */
  public XSObject item(int index) {
    if (index < 0 || index >= fLength) {
      return null;
    }
    return fArray[index];
  }

  // clear this object
  public void clearXSObjectList() {
    for (int i = 0; i < fLength; i++) {
      fArray[i] = null;
    }
    fArray = null;
    fLength = 0;
  }

  public void addXSObject(XSObject object) {
    if (fLength == fArray.length) {
      XSObject[] temp = new XSObject[fLength + 4];
      System.arraycopy(fArray, 0, temp, 0, fLength);
      fArray = temp;
    }
    fArray[fLength++] = object;
  }

  public void addXSObject(int index, XSObject object) {
    fArray[index] = object;
  }

    /*
     * List methods
     */

  public boolean contains(Object value) {
    return (value == null) ? containsNull() : containsObject(value);
  }

  public Object get(int index) {
    if (index >= 0 && index < fLength) {
      return fArray[index];
    }
    throw new IndexOutOfBoundsException("Index: " + index);
  }

  public int size() {
    return getLength();
  }

  public Iterator iterator() {
    return listIterator0(0);
  }

  public ListIterator listIterator() {
    return listIterator0(0);
  }

  public ListIterator listIterator(int index) {
    if (index >= 0 && index < fLength) {
      return listIterator0(index);
    }
    throw new IndexOutOfBoundsException("Index: " + index);
  }

  private ListIterator listIterator0(int index) {
    return fLength == 0 ? EMPTY_ITERATOR : new XSObjectListIterator(index);
  }

  private boolean containsObject(Object value) {
    for (int i = fLength - 1; i >= 0; --i) {
      if (value.equals(fArray[i])) {
        return true;
      }
    }
    return false;
  }

  private boolean containsNull() {
    for (int i = fLength - 1; i >= 0; --i) {
      if (fArray[i] == null) {
        return true;
      }
    }
    return false;
  }

  public Object[] toArray() {
    Object[] a = new Object[fLength];
    toArray0(a);
    return a;
  }

  public Object[] toArray(Object[] a) {
    if (a.length < fLength) {
      Class arrayClass = a.getClass();
      Class componentType = arrayClass.getComponentType();
      a = (Object[]) Array.newInstance(componentType, fLength);
    }
    toArray0(a);
    if (a.length > fLength) {
      a[fLength] = null;
    }
    return a;
  }

  private void toArray0(Object[] a) {
    if (fLength > 0) {
      System.arraycopy(fArray, 0, a, 0, fLength);
    }
  }

  private final class XSObjectListIterator implements ListIterator {

    private int index;

    public XSObjectListIterator(int index) {
      this.index = index;
    }

    public boolean hasNext() {
      return (index < fLength);
    }

    public Object next() {
      if (index < fLength) {
        return fArray[index++];
      }
      throw new NoSuchElementException();
    }

    public boolean hasPrevious() {
      return (index > 0);
    }

    public Object previous() {
      if (index > 0) {
        return fArray[--index];
      }
      throw new NoSuchElementException();
    }

    public int nextIndex() {
      return index;
    }

    public int previousIndex() {
      return index - 1;
    }

    public void remove() {
      throw new UnsupportedOperationException();
    }

    public void set(Object o) {
      throw new UnsupportedOperationException();
    }

    public void add(Object o) {
      throw new UnsupportedOperationException();
    }
  }

} // class XSObjectListImpl
